This invention pertains to a fastener assembly and more particularly to a nut plate fastener assembly for use with bolted members and a method for making the nut plate.
Fastener assemblies are used in many applications to, for example, fasten components to one another. One common type of fastener assembly is a threaded nut and bolt combination.
While nuts and bolts have been used for fastening for decades and perhaps centuries, they can at times, and in certain circumstances be difficult to manipulate into engagement with one another. Specifically, in a typical application, a bolt is inserted through openings in the components to be fastened to one another and a nut is threaded on to the bolt. Generally, either the bolt head or the nut must be maintained fixed while the other is rotated to engage the threads and secure the fastening assembly. This can be quite difficult where the nut is in a xe2x80x9cblindxe2x80x9d location where a user cannot see whether the nut is properly located, or the bolt is properly threadedly engaged with the nut. This can be even more difficult when the nut is in a location that is difficult to reach vis-a-vis limited accessibility.
To this end, nut plates have been used on which a nut is mounted to a plate, which plate is mounted to one component that is secured to another component. These nut plates have found many uses, such as in automobile assembly for bumper attachments, trailer hitch attachments and the like.
An example of a nut plate is disclosed in Stewart et al., U.S. Pat. No. 5,971,686 entitled Retained Fastener. One embodiment of the assembly disclosed in Stewart et al. is a generally U-shaped clip having elongated legs. A nut is disposed through an opening in one of the legs, which nut is inserted between the legs from about a central portion of the clip. The nut is then secured to the clip at the comers of the nut.
While the retained fastener disclosed in Stewart et al. may well serve certain functions it does, in fact, have its drawbacks. One such drawback is that the nut is inserted into the central portion of the clip prior to the bending of the legs. This can add considerably to the overall fabrication and/or assembly costs of such a fastener device. Alternately, the clip may be formed, e.g., stamp and bent, and the legs of the clip spread to insert the nut. In that these fasteners are commonly used and may be used in considerably large quantities, it would be desirable to maintain the cost of such assemblies as low as is reasonably achievable.
Another assembly is disclosed in Stewart et al., U.S. Pat. No. 5,934,851 entitled Staked Fastener Having Wrenchable Flats. In this Stewart et al. patent, it appears that rather a complex assembly is used for affixing or mounting the nut to the plate. Again, such a complex assembly could add to the overall costs of manufacturing or fabricating such a fastener device which, again, is undesirable.
Another drawback to these assemblies is that the material may require heat treatment in order to achieve specified mechanical properties, such as increased toughness and ductility. Typically, heat treatment is carried out after formation and working of the clip material. In that known nut plates either have the nuts inserted before working, e.g., bending, or require that he clip legs be spread to insert the nuts, it is both difficult and costly, if even practical to heat treat known nut plate assemblies.
Accordingly, there exists a need for a nut plate-type fastener assembly in which the plate can be fully fabricated prior to positioning a nut therein. Desirably, such a nut plate can be manufactured from post forming treated materials, e.g., heat treated materials, without adversely affecting the characteristics of the plate material. Additionally, it is desirable for such a nut plate to be heat treated without adversely affecting the mechanical properties, e.g., strength, ductility, and the like, of the nut that is positioned in and mounted to the plate.
A nut plate includes a generally U-shaped clip having first and second elongated legs and a connecting leg extending therebetween. The first leg has an opening for receipt of a nut and for securing the nut in the leg. The second leg has a pass-through opening in opposing relation to the nut opening. The nut can be fully passed through the pass-through opening and positioned in the first leg without deflection and urging away of the legs from one another.
In a current embodiment, the nut plate includes two nut openings and two pass-through openings, one associated with each of the nut openings. Both of the nuts can be positioned in the first leg nut openings without deflection and urging away of the legs from one another.
The nut plate can be manufactured from post-forming treated materials, that is, it can be heat treated and the nut subsequently assembled without adversely affecting the characteristics of the plate material. To this end, a preferred nut plate is formed from heat treated material. The clip is stamped and formed, e.g., bent, and is heat treated after stamping and forming.
The nut plate can be formed having an enlarged, arcuate extension region at about each nut opening. One or both of the legs can be formed to define an enlarged entrance region into the clip.
The pass-through openings can be formed as enlarged circular openings having a diameter slightly larger than a distance across opposing apices of the nut or the diameter of the nut flange. Alternately, the pass-through openings can be formed having other shapes, such as a xe2x80x9cDxe2x80x9d shaped configuration. To provide better contact between the nut plate and the component to which it is mounted, the first leg can be formed having a raised area surrounding each of the nut openings.
A method for forming the nut plate includes the steps of forming an elongated strip, forming a nut opening in the strip, forming a pass-through opening in the strip, and bending the strip to define first and second legs and a connecting leg. The nut opening is formed in the first leg and the pass-through opening is formed in the second leg opposing the nut opening. The method further includes passing a nut through the pass-through opening into the nut opening and securing the nut to the first leg.
A preferred method includes heat treating the strip after bending and prior to passing the nut through the pass-through opening.
A current method includes forming two nut openings in the strip, forming two pass-through openings in the strip and passing a nut through each of the pass-through openings into a respective nut opening.
These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims.